Protective link for a transformer or such like device enclosed within a tank



Oct. 21, 1969 M. G. LEONARD 3,474,374

PROTECTIVE LINK FOR A TRANSFORMER OR SUCH LIKE DEVICE ENCLOSED WITHIN A TANK Filed Sept. 19, 1966 2 p fez fez FlG.2. w

AM 39 4 V 72 WITNESSES s2 IINVENTOR Mf /QM I as "k\\ Merrill G.Leonord BY 4% 1 84 W21 v 7 A ORNEY United States Patent PROTECTIVE LINK FOR A TRANSFORMER R SUCH LIKE DEVICE ENCLOSED WITHIN A TANK Merrill G. Leonard, Fowler, Ohio, assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Sept. 19, 1966, Ser. No. 580,285 Int. Cl. H01h 85/22 U.S. Cl. 337-207 6 Claims ABSTRACT OF THE DISCLOSURE A fuse housing adapted to be mounted on the inside end of a conductor stud passing through a bushing mounted in an aperture in a transformer tank or other enclosing devise, with the external end of the conductor stud being adapted to have a connection made thereto. Disposed near the bushing having the conductor stud is a smaller bushing threaded internally adapted to receive the handle end of a bar or rod which has a fuse being adapted to be slid into position in the fuse housing or fuse holder, the fuse having a pair of electrodes at the two ends of a fuse tube, fuse wire means within the fuse tube having the ends thereof electrically connected to the electrodes respectively, the fuse holder having spring means for making electrical connection at the electrode at one end of the fuse to the conductor stud, and spring means at the other end of the fuse for making electrical connection to a lead wire to the transformer or other device.

This invention relates to improvements in protective links, and more particularly to a protective link suitable for use with a transformer or such like electrical device enclosed within a tank.

In summary, my invention in one embodiment thereof includes a fuse housing adapted to be mounted on the inside end of a conductor stud passing through a bushing mounted in an aperture in a transformer tank or other enclosing device, with the external end of the conductor stud being adapted to have a connection made thereto. Disposed near the bushing having the conductor stud is a smaller bushing threaded internally adapted to receive the handle end of a bar or rod which has a fuse secured to the other end thereof, the fuse being adapted to be slid into position in the fuse housing or fuse holder, the fuse having a pair of electrodes at the two ends of a fuse tube, fuse wire means within the fuse tube having the ends thereof electrically connected to the'electrodes respectively, the fuse holder having spring means for making electrical connection at the electrode at one end of the fuse to the conductor stud, and spring means at the other end of the fuse for making electrical connection to a lead wire to the transformer or other device.

In summary, in another embodiment of my invention, a fuse housing composed of electrically insulating material is mounted at a convenient position within the tank, the fuse housing having two spring-biased electrical connectors thereon one of which is adapted to be connected to the conductor stud which passes through the high voltage bushing or other electrical connection made thereto, and the other of which is adapted to be connected to lead means inside the tank, the fuse being connected to and forming an extended end portion of arm means which is adapted to be inserted into the fuse housing,the fuse including fusible wire means connected at each end thereof to electrodes on the ends of the fuse, adapted to make electrical connection with the spring-biased electrical connectors or terminal means while the fuse is inserted in the fuse housing.

3,474,374 Patented Oct. 21, 1969 Accordingly a primary object of my invention is to provide a new and improved protective link for a transforrlgier of such like device which is enclosed within a tan Another object is to provide a new and improved protective link which may be replaced through a suitable opening in the tank wall without necessitating a large opening in the tank structure.

A further object is to provide a new and improved protective link including a fuse and having new and improved means for making electrical contact between electrodes at the end of the fuse and contact means disposed in or on the fuse housing.

These and other objects will become more clearly apparent after a study of the following specification, when read in connection with the accompanying drawings, in which:

FIGURE 1 is a view of my invention according to one embodiment thereof;

FIG. 2 is a view partially in section of a fuse housing according to a second embodiment of my invention; and

FIG. 3 is a view of a fuse having an extended arm portion for mounting in the fuse housing of FIG. 2.

Referring now to the drawings, in which like reference numerals are used throughout to designate like parts, for a more detailed understanding of the invention, and in particular to FIG. 1, a portion of a tank 10 is shown having adjacent apertures 11 and 12 in a wall thereof. In aperture 12 there is disposed a high voltage bushing 13 having a conductor stud 14 extending therethrough, and having secured on the inside end 15 thereof a mounting bracket 16 composed of electrically conductive material, the bracket 16 being held in place by nut 17.

The bracket 16 has an aperture 9 therein in which is disposed a fuse guide sleeve 20 composed of electrically insulating material, having an upper flaring throat portion 19 and a lower extended cylindrical portion 22. The cylindrical portion of the guide sleeve has two slots 42 and 38 therein spaced apart from each other, through which extend respectively spring contacts 43 and 37, the spring contact 43 being secured by bolt or rivet 44 to the mounting bracket 16 and making electrical connection therewith, the spring contact 37 being secured by bolt or rivet 39 to the insulating portion 22 of the guide sleeve, spring contact 37 having secured thereto as by soldering a lead wire 36 which it is understood goes to electrical apparatus, not shown within the tank for convenience of illustration.

The aforementioned protective link generally designated 28 includes a fuse tube 23 having an upper electrode 24 mounted thereon and a lower electrode 25 mounted thereon in positions whereby while the protective link is disposed within the guide sleeve the electrodes 24 and 25 are in electrical contact respectively with the spring contacts 43 and 37. A fuse element, which may be a fuse wire, is shown at 26 extending from the lower end of the fuse tube 23 and is soldered at 27 to the electrode 25.

Other means of attaching this fuse wire 26 to the electrode 25 may be employed. For example, the bottom end of the fuse wire may be crimped against the fuse tube, or a notch may be provided under the electrode for crimping the fuse wire therein.

The top end of the fuse wire 26, not shown for convenience of illustration, is soldered to a spade or stud extending down inside the top electrode 24 and electrically connected thereto. This electrode 24 is threaded internally, and the adjacent end of the fuse tube 23 is threaded externally. It is seen that the protective link 28 has an extended upper portion 30 with a bore therein, in which is seated and securely attached by bolt or screw 31 a pull tached at its upper end to a head or handle'member 48 having a threaded portion 50 engaging internal threads in the bushing 51 in the aforementioned aperture 11 in the tank, the handle also having the eye-forming portion 49. By grasping the eye 49 and unthreading the head portion 50 or 48, the protective link 28 is released and may be withdrawn from the transformer tank and the fuse or the fuse element replaced, after which the new protective link may be reinserted into the guide sleeve generally designated 20.

The aforedescribed embodimnt of FIG. 1 provides a fusible element, which is desirable under some conditions of operation, in the primary side of the transformer, which will protect against a fault either in the primary winding or in the secondary circuit. Generally speaking, such systems are subject to rather frequent faults and therefore it is desirable that the fusible element be readily replaceable, an object which I have accomplished by my described structure.

It is to be noted that the bottom electrode 25 is placed back a short distance from the end of the fuse tube. This construction results in the formation of a current loop around the end of the fuse tube, and when the fuse blows this loop, as it expands and stretches in length, forces the are into the fresh oil below or around the tube, in much the same way that the blow-out electrode does in a present standard or conventional fuse.

The presence of the bottom electrode on the outside of the tube provides a convenient surface for contact with the spring terminal.

It is further to be noted that at the top of the protective link it is attached to an insulating rod which is securely supported in the aforementioned threading fitting 48. The fitting may be turned by a hook stick in the eye 49, and the entire assembly may be unscrewed from the flange 51, which is welded in the cover 10.

The guide structure for the link is seen to be supported in fixed position with respect to the high voltage bushing by means of a bracket. This bracket also serves to carry current to the fuse link.

In usual practice, the link is connected to carry only the current to the high voltage coil. If a through current is required for loop feed, this would be carried between two similar high voltage bushings by a suitable bus bar, not shown for convenience of illustration.

Part of the novelty of my invention resides in the use of a protective link with a fusible element, loop shaped at the bottom end, and attached to a lower electrode on the outside surface of a tubular housing.

An additional part of the novelty of my invention resides in the combination of the protective link with sealed and removable fittings.

Particular reference is made now in FIG. 3. The protective link 60, having upper and lower contacts or electrodes 61 and 62 respectively, has an extended flat plate portion 63 with a bore 64 therethrough formed integrally with the upper contact 61. This plate portion 63 fits in a slot 65 in the end of an insulating rod 66 and is held in place therein by set screw 67. The hook stick eye 68 has adjacent thereto a flange portion 69, and a threaded shaft portion 70.

The fuse wire 72 is seen to extend from the bottom of the link 60 and to have the end thereof crimped'under the electrode or contact 62.

The structure of FIG. 3 is designed to be plugged into the receptacle shown in FIG. 2, the receptacle generally designated 75 being composed of insulating material and having one end thereof extending through a bore or opening 77 in transformer tank 78, and to be held adjacent the tank wall 78 by the flange portion 79 and secured in position by any convenient means, not shown. The receptacle generally designated 75 has mounted thereon at spaced intervals two contact holders 81 and 82, contact holder 81 being secured to the receptacle by screws 83,

and contact holder 82 being secured to the receptacle by screws 84. A cross-section is shown through the contact holder 82, which is seen to include a movable contact member 86 composed of electrically conductive material, spring-biased by coil spring 87, the spring contact member 86 having lead 92 secured thereto which passes through a bore 94 in member or contact holder 82. Lead 91 passes through a similar bore, not shown for convenience of illustration, in contact holder 81, and makes electrical connection with a spring contact therein, not shown for covenience of illustration.

It will be understood that the contact member 86 and the corresponding contact member located in the contact holder 81 are so spaced with respect to each other as to make a firm electrical connection with the contacts or electrodes 61 and 62 while the plug-in protective link is plugged into the receptacle shown in FIG. 2. It will be further understood that the aforementioned threads 70 engage threads 96 on' the inside surface of the upper end of the aforementioned receptacle assembly 75.

In the embodiment of FIGS. 2 and 3 then, there has been provided another plug-in protective link offering advantages similar to those of the embodiment of FIG. 1, in that there is the combination of the link with the sealed and removable fitting, and that the protective link has a fusible element loop-shaped at the bottom end and attached externally to the fuse housing to the lower electrode secured on the outside surface of the tubular fuse housing.

In testing apparatus embodying the invention, it has been noted that there is a tendency for are gases expelled from the bottom end of the tube to envelope the outer portion for a considerable distance. To prevent the are from restriking over the outside, exposed metal at the top contact, FIG. 1, is kept to a minimum, or covered by insulation, not shown for convenience of illustration.

To prevent the arc from restriking between the exposed high voltage bushing stud and the tank wall, all exposed high voltage terminals and connections are covered with insulating material, not shown for convenience of illustration.

Whereas I have shown and described my invention with respect to two embodiments thereof which give satisfactory results, it should be understood that the drawings and written description are illustrative only and should not be interpreted in a limiting sense.

I claim as my invention:

1. In protective fuse link apparatus for use with electrical equipment, the combination of a standoff insulator adapted to be mounted in the wall of a tank containing electrical equipment and extending from said wall toward the interior of the tank, fuse receiving means secured to the inside end of the standoff insulator, the fuse receiving means including a tubular portion and a flaring throat portion through which a fuse is inserted and guided to position within the tubular portion, a pair of spring electrical contact means in the tubular portion near the ends thereof respectively, the wall of said tank being adapted to have threaded aperture forming means therein in predetermined position with respect to said standoff insulator, a fuse disposed in said tubular portion, the fuse including a fuse tube, a fuse element and a pair of annular electrodes on the fuse tube near the ends thereof respectively making electrical connection with the ends of the fuse element and with the pair of spring electrical contact means respectively, and fuse-inserting rod means attached to one end of the fuse tube and extending through said threaded aperture forming means in threaded engagement therewith.

-2. In protective fuse link apparatus for use with electrical equipment, the combination of an insulator adapted to be mounted in the wall of a tank containing electrical equipment and extending from said wall toward the interior of the tank, fuse receiving means secured to the inside end of the insulator, the fuse receiving means including a tubular portion, a pair of spring electrical contact means in the tubular portion near the ends thereof respectively, a fuse disposed in said tubular portion, the fuse including a fuse tube, a fuse element and a pair of contact means on the fuse tube near the ends thereof respectively making electrical connection with the ends of the fuse element and with the pair of spring electrical contact means respectively, the tank having an aperture in the wall thereof in predetermined spaced position with respect to said insulator, said fuse being adapted to be placed in position in the fuse receiving means through said aperture.

3. Apparatus according to claim 2 in which the insulator is additionally characterized as having a conductor stud passing therethrough, and in which the fuse receiving means is at least partially composed of conductive material and forms a conductive path from one of the spring electrical contact means through the conductor stud to the outside of the tank.

4. In protective fuse link apparatus for use with electrical equipment, the combination of an insulator adapted to be mounted in the Wall of a tank containing electrical equipment and extending from said wall toward the interior of the tank, a conductor stud passing through said insulator, fuse housing and fuse supporting means including a tubular portion composed of insulating material, bracket means composed of conductive material securing the fuse housing and fuse supporting means to the inner end of the conductor stud, a pair of spring electrical contact means in the tubular portion near the ends thereof respectively, one of said spring electrical contact means being electrically connected to the bracket means of conductive material and completing an electrical circuit from the last named spring electrical contact means through the bracket means and the conductor stud to the outside of the tank, a fuse disposed in said tubular portion, the fuse including a fuse tube, a fuse element and a pair of contact means on the fuse tube near the ends thereof respectively making electrical connection with the ends of the fuse element and with the pair of spring electrical contact means respectively, the tank having an aperture in the wall thereof in predetermined spaced position with respect to said insulator, and means including rod means and aperture closing means for inserting the fuse into the fuse housing through the aperture and thereafter closing the aperture.

5. Fuse means adapted for use in a tank containing electrical equipment including a tubular housing composed of insulating material adapted to be mounted in an aperture in the wall of the tank, the tubular housing having first and second apertures in the wall thereof at axially spaced positions, first and second electrical contact members extending through said first and second apertures respectively, first and second contact housings secured to said tubular member and enclosing said first and second apertures respectively, first and second spring members each having one end abutting against a contact member and the other end abutting against the wall of a contact housing, the housings each having a bore therethrough, first and second electrical leads passing through said bores and making direct electrical connection with the first and second contact members respectively, a fuse disposed within the tubular member, the fuse including a fuse tube, a fuse element, and first and second annular electrodes around the fuse tube near the ends thereof electrically connected to the ends of the fuse element respectively and making contact with the first and second contact members respectively, and insulating rod means easily detachable from the fuse secured at one end thereof to the fuse and extending through the tubular housing, the tubular housing and rod having cooperating means near the outer ends of both for securing the rod in position within the tubular housing.

6. Fuse means adapted for use in a tank containing electrical equipment including a tubular housing composed of insulating material adapted to be mounted in an aperture in the wall of the tank, the portion of the inside wall of the tube adjacent the wall of the tank being threaded, the tubular housing having first and second apertures in the wall thereof at axially spaced positions, first and second electrical contact members extending through said first and second apertures respectively, first and second contact housings secured to said tubular member and enclosing said first and second apertures respectively, first and second spring members each having one end abutting against a contact member and the other end abutting against the Wall of a contact housing, the housings each having a bore therethrough, first and second electrical leads passing through said bores and making direct electrical connection with the first and second contact members respectively, a fuse disposed Within the tubular member, the fuse including a fuse tube, a fuse element, and first and second electrodes around the fuse tube near the ends thereof electrically connected to the ends of the fuse element respectively and making contact with the first and second contact members respectively, and insulating rod means secured at one end thereof to the fuse tube and having the other end thereof threaded to engage said threaded portion of the inside wall of the tubular housing.

References Cited UNITED STATES PATENTS 2,918,557 12/1959 Link 200113.3 3,365,616 1/1968 Henmann 31715 BERNARD A. GILHEANY, Primary Examiner R. L. COHRS, Assistant Examiner US. Cl. X.R. 3372l7 

